EARLY HUMAN DEVELOPMENT Passive smoking affects neurodevelopment in babies

Newborns exposed to nicotine from both active and passive smoking mothers show poor physiological, sensory, motor and attention responses. These are the results of new research carried out in the Behaviour Evaluation and Measurement Research Centre (CRAMC) of the Universitat Rovira i Virgili in Spain, and published in the journal Early Human Development.

Smoking is still widespread in Europe. Approximately 29 per cent of Europeans smoke and 695 000 Europeans die prematurely of tobacco-related causes, making it the largest single cause of preventable death. In financial terms, smoking costs the EU countries at least EUR 100 billion. Smoking during pregnancy is one of the biggest yet avoidable causes of illness and death for both mother and infant. Nonetheless, epidemiological studies show that between 11 % and 30 % of pregnant women smoke or are passively exposed to tobacco smoke.

This new research may make smokers take note of the impact their smoking has on infants and their development.

Smoking during pregnancy has already been linked to many different problems in infants like learning difficulties, attention deficit disorder with hyperactivity and even obesity. The mothers are also affected, as statistics show that women who smoke during pregnancy are more likely to have vaginal bleeding, placental abruption or a stillbirth. However, while the paediatric and obstetric disorders linked to tobacco during this stage have been well documented, the effects on neonatal behaviour have not yet been studied in depth.

The new study, headed by experts at the CRAMC tries to bridge this knowledge gap and analyses the effects of passive smoking during pregnancy on the newborn.

The scientists began by evaluating the behaviour of 282 healthy newborns using the Neonatal Behavioural Evaluation Scale. This allows for interaction with the newborn in order to evaluate its behaviour and responses between 48 and 72 hours after birth.
From those mothers studied, 22 per cent smoked during pregnancy, while close to 6 per cent were exposed to passive smoking. Out of the smoking mothers, 12.4 per cent had between 1 and 5 cigarettes a day, 6.7 per cent had between 6 and 10 a day; and 2.8 per cent had between 10 and 15 a day. None smoked more than 15 cigarettes a day.

'Newborns who have had intrauterine exposure to nicotine, whether in an active or passive way, show signs of being more affected in terms of their neurobehavioural development. This could be an indicator of pathologies, independently of sociodemographic, obstetric and paediatric factors,' explains Josefa Canals, the lead author of the study.

The results reveal that those born to smoking and passive smoking mothers score low in their ability to inhibit stimuli that could alter the central nervous system. Furthermore, children of passive smoking mothers have poor motor development and those of smoking mothers have less ability to regulate behaviour and response in physiological, sensor, motor and attention terms.

'Health professionals should encourage future mothers and their families to eliminate or reduce tobacco consumption,' states Professor Canals, who outlined the importance of informing mothers on the effects of involuntary exposure to cigarette smoke in order to prevent direct damage to the foetus and infant development. When a pregnant woman smokes, nicotine concentrations in the foetus outstrip those found in the mother by more than 15 per cent. In Spain, 43.5 per cent of women between 25 and 44 years of age smoke, but during pregnancy this percentage falls to approximately 26.6 per cent.

'However, although women tend to reduce their normal tobacco consumption when falling pregnant, the key is to study the effects of exposure to small amounts of smoke on foetal development,' concluded Professor Canals.